Dual unloading system



y 30, 1933- I H. v. HAIGHT 1,911,951

DUAL UNLOADING' SYSTEM Filed Jan. 6. 1951 2 Sheets-Sheet 1 Hi5 ATTORNEY.

Patented May 30, 1933 UNITED STATES PATENT OFFICE HARRY V. IdAIGHT,SHERIBROOKE, QUEBEC, CANADA, ASSIGNOR 'I'O INGERSOLL- RAND GOMPANY, OFJERSEY CITY NEW JERSEY, A CORPORATION OF NEW JERSEY DUAL UNLOADINGSYSTEM Application filed January 6, 1931. Serial No. 506,925.

This invention relates to compressor unloaders, and the ob ectS of theinvention are to enable the compressor to be quickly and convenientlyunloaded both on starting and stopping and also to be unloaded orreloaded as required during operation, depending on the load.

In accordance with this invention the compressor is provided with aplurality of unloading systems arranged to unload the compressor eitherby one system or the other, but incapable of reloading the compressorunless both systems tend to reload. One system or the other may unloadthe compressor, but the operation of both systems is required to reloadthe compressor.

In this way one system or the other may be selected for the unloadingoperation, and one system may be an automatic system while the other ismanually controlled. A controlling valve is preferably provided forautomatically bringing one system or the other into operation andanother valve is provided for selecting the system for operation. Theautomatic controlling valve also prevents the reloading of thecompressor unless both systems are operative for reloading.

The drawings illustrate preferred forms of the invention, in whichFigure 1 is a diagrammatic representation partly in vertical section andpartly broken away, showing the dual unloading system applied to ,onecylinder of a compressor, and

Figure 2 is a similar view of the dual system applied to the twocylinders of a compound compressor.

Referring to the drawings and at first more particularly to Figure 1,the compressor cylinder A has the piston B driven from the belt wheel Cby means of an electric motor (not shown). The air enters at the intakeD and is discharged through the discharge pipe E into the receiver F inthe usual manner. The cylinder is provided with the inlet valves G andthe discharge valves H. In this instance the inlet. valves are providedwith valve openers in the form of pistons J operating in the cylinders Kand these pistons have fingers L for bold ing the inlet valves away fromtheir seats when pressure fluid is supplied to the cylinders K throughthe 'pipes 0. These Valve openers constitute unloading devices forunloading the compressor.

Two unloading systems are provided for operaLing the unloading devicesand one system includes the valve parts associated with the valve casingP and electro-magnet Q controlled from the switch R and the other systemincludes the valve mechanism associated with the valve casing S. Bothsystems are controlled by the automatic con- Figure 1 in which case thelever X will be' rocked on its pivot Y and the lever arm Z will forcethe pin a upwardly and cause the ball valve b to be seated while the pinwill force the ball valve (Z away from its seat against the tensionspring 6. Pressure fluid from the receiver F will then pass through thepipe f and with the manually controlled valve 9 in the position shown inthe Valve casing U, the receiver pressure will pass through pipe h tothe valve casing P, thence through the pipe 9 to the valve casing T ofthe controlling valve. The ball valve 1' in the valve casing T will beforced to its seat as indicated in Figure 1 and pressure fluid will passthrough the apertures s in the valve cage and through the pipe to thetwo pipes 0 leading to the unloading device cylinders K. The inletvalves will be held away from their seats and the compressor cylinderwill be unloaded.

The manually controlled valve U when in the position shown in Figure 1prevents fluid pressure from the receiver F from passing through thepipe f to the pipe u leading to the auxiliary valve casing S so that thesystem of unloading including the valve in the casing S is inoperativefor unloading the compressor. This is for the reason that pressure isrequired to lift the piston '12 forming the valve in the casing S whichpiston is held to its seat by the spring w, compressed between the head.r on the stem y and the end of the sleeve 2. There is sufiicientclearance between the sleeve 2 and stem 3 to form a vent leading toatmosphere at the vent port 3. The pipe 4 connects the side of thecylinder S with the valve casing T of the automatic controlling valve sothat the left hand side of the ball valve '2' as shown in Figure 1 isvented through the pipe 4 to atmosphere through the valve casing S andthrough the vent 3. The unloading system including the valve casing Sand.

valve 0 is thus in condition to vent the unloading device cylinders Kand permit reloading of the compressor when the ball valve 1' is removedfrom its seat.

To reload the compressor, the electric switch R is closed and the magnetQ energized which rocks the lever X and releases the ball valve b sothat this valve is removed from its seat and the ball valve (Z becomesseated, thus shutting off the supply of pressure fluid to the automaticvalve in the easing T and opening said valve casing through the pipe 5either "to atmosphere orto the intake D as shown in the drawings. Thebacks of the pistons J in the unloading device cylinders K are thusrelieved of pressure both through the valve casing P and through thevalve casing S and the compressor cylinder is reloaded. The electricswitch It may be connected to be operated automatically from the circuitincluding the motor which drives the compressor so that the compressoris unloaded on starting and stopping, but these connections are notshown as they are the usual start and stop connections.

Let it be assumed. that the valve 9 is turned to the opposite positionby turning the handle 6 counter-clockwise. in which case pressure fluidwill be cut off between the pipes f and h and pressure fluid will besupplied from the receiver F through the )ipe U to the valve piston o inthe casing S o the auxiliary valve and when the pressure in the receiveris sufiicient this valve Q] will be raised from its seat 7 and the upperend will be seated on the seat 8. The pressure fluid will then passthrough the pipe 4 to the automatic controlling valve in the casing T,which will unseat the ball valve 1 and pressure fluid will be suppliedthrough the pipe t and pipes O to the backs of the pistons J of theunloading devices which will unload the compressor. A suflicientreduction of pressure in the receiver F will cause the valve 0 in thecasing S to be retracted into the initial position shown In thedrawings,

which will open the pipe 4 to the vent 3 but tion is brought about byclosing the switch R, raising the lever X and lowering the pin a so thatthe ball valve 6 opens communication between the pipe q and the ventpipe 5.

The ball valve "1' will then assume a neutral position and the ventingrelief of pressure behind the unloading device pistons J may take place.

In accordance with the invention so far described it will be observedthat the position of the manual valve 9 determines the selection of theunloading system which is to operate the unloading devices and unloadthe compressor. In order, however, that the compressor may be reloaded,both unloading systems must be in reloading conditions or must tend toreload before the reloading can take place.

In Figure 2 the invention is shown applied to a compound compressorhaving a low pressure cylinder 9 and the high pressure cylinder 10. Thepistons 12 and 13 are driven from the crank shaft 14 in any suitablemanner. The cylinders are provided with the usual inlet and dischargevalves G and H and the inlet valves are provided with the valve liftersL carried by the pistons J in the cylinders K thus forming unloadingdevices as in Figure 1. These unloading devices J, K, L form free airunloading devices, so called because the inlet valves are held open andpermit air to pass freely in and out of the cylinders for unloadingpurposes. The air enters the low pressure cylinder at the inlet 15 andis discharged through the outlet 16 and after passing-through theintercooler (not shown) enters at the inlet 17 of the high pressurecylinder and is discharged from the discharge outlet 18 of the highpressure cylinder to the receiver tank F shown at the top of Figure 2,it being understood that there is a connection between the dischargeoutlet 18 of the high pressure cylinder and the receiver F not shown forsimplicity.

In addition to the free air unloading devices J, K, L the cylinders areprovided with clearance unloaders and in this instance clearancechambers 19 and 20 are shown in the cylinder heads 21 and 22 at thecrank pressor adapted to contain clearance valves or controllingclearance chambers in the head ends.

One unloading system is provided for operating the free air unloaders orvalve lifters L and another unloading system is provided for operatingthe clearance valves 23 in both the head and crank ends of thecylinders. These two unloading systems are so devised and arranged thateither system may be used for unloading the compressor, but thecompressor cannot be reloaded until both systems are in reloadingcondition.

An automatic regulator of any suitable or usual type, as for instancethat shown in United States Patent No. 1,588,257 granted June 8, 1926 toChester W. Metzgar for Compressor unloader may be provided forautomatically controlling the free air unloaders L. This regulator isshown partly broken away at the upper left hand corner of Figure 2 andcomprises a lever 26 pivoted at 27 on a casing 28 which contains adiaphragm 29 subject to receiver pressure through the pipe 30.

A pin 31 hearing against the lever 26 is actuated by the diaphragm 29 toraise and lower said lever. The weight 32 on the lever may be adjustedalong its'length for balancing purposes.

The valve stem 33 of a pilot valve 34 is pivoted at 35 to the lever 26and the movement of the pilot valve 34 controls main valves 36 in theregulator valve casing, only one of said valves 36 being shown. Thevalve chamber of the pilot valve 34 is supplied with pressure fluid fromthe receiver F through the pipe 37 and the lower end of said valvechamber is vente through the pipe 38. The valve chambers of the mainvalves 36 are supplied with pressure fluid from the diaphragm chamberthrough the passage 39.

The operation of the automatic regulator is fully set forth in PatentNo. 1,588.25? and will only be briefly described.- Assuming that thepilot valve 34 is in its lowermost position as indicated in Figure 2.all the valves 36 of which there are two in this case, will be in theirright hand position as indicated by the valve 36 shown in sectionbecause pressure fluid entering through the pipe 37 passes through thepassage 40 to the main valve 36 and the opposite end of said valve isvented through the passage 41 to atmosphere through the upper open end42 of the pilot valve casing. Pressure fluid can then pass through thepassage 39 around the valve 36 and through the passage 43 to the pipe 44to the casing of the controlling valve 45 and assuming that the ballvalves 46 and 47 in the casing 45 are in neutral position owing to theintroduction of pressure fluid at each end of the casing the pressurefluid will pass on around valve Pressure fluid is supplied to the righthand end of the valve casing 45 under such conditions through the pipe50 and through the valve casing P which is similar to the valve casing Pshown in Figure 1 and contains the same ball valves Z) and (Z. Since theswitch It is open the electro-magnet Q is deenergized and the ball valve6 is seated while the valve '(l is unseated and pressure fluid issupplied from the branch pipe 51 to the casing P and around the ballvalve d to the pipe 50, thus as described introducing pressure fluid atthe right hand. end of the valve casing 45. This pressure fluid may alsopass through the pipe 48 to the clearance valves.

In a similar manner pressure fluid is being supplied from the regulatorthrough the pipe 52 to and through the valve casing 53 similar to thevalve casing 45 and through the pipe 54 and branch pipe 55 to theclearance valves at the crank end of the high prcsssure cylinder and thehead end of the low pressure cylinder so that these valves are held totheir seats in loading position. Pressure fluid is also supplied to theright hand end of the Valve casing 53 through the pipe 56 leading to thevalve casing P which is similar to the valve casing P and the parts insaid valve casing are in similar position. Pressure fluid is led to thevalve casing P through the pipe 57 connected to the pipe 30, and in theposition of the parts in Figure 2 passes around the ball valve (Z to thepipe 56.

Pipe 37 is continued from the point at which it leaves the casing of theautomatic regulator and is connected to the casing T of an automaticcontrolling valve actuated by an electro-magnet Q having the weightedcore W, suspended from the lever arm 58 pivoted at 59 on the valvecasing and having the arm 60 for actuating the pin 61 extending into thevalve casing. The ball valves 62 and 63 are separated by the pin 64 anda spring e bears on the ball valve 63. A pipe 65 leads from the casing Tto the unloader valve casings K on the cylinders which contain thepistons J for the inlet valve openers, and when pressure fluid issupplied through the pipe 65 the inlet valves G are lifted from theirseats for unloading both cylinders.

The valve casing T is provided with the vent 66 and in the position ofthe parts shown in Figure 2 the pipe 65 is vented to atmosphere throughthe pipe 66 because the switch R is open the magnet'Q, is deenergizedand the weighted core W has rocked the lever arm 58 to permit the ballvalve 62 i to open. Upon closure of the switch R which energizes themagnet Q the core W will be retracted, the. ball valve 62 will be forcedto its seat and the ball Valve 63 lifted from its seat so that pressurefluid will be supplied through the pipes 37 and 65 to operate the inletvalve lifters J.

It is to be understood that the automatic regulator having the pivotedlever 26 shown at the upper left hand corner of Figure 2 in conjunctionwith the automatic valves in the valve casings 45 and 53 and the pipesand connections leading to the clearance valves 23 constitute one systemof unloading, while the automatic valve in the casing T in combinationwith the inlet valve lifters J constitutes another system of unloading.The switch R controls electro-responsive devices Q, and Q in bothsystems and the arrangement and construction is such that either onesystem or the other may unload the compressor but both systems arerequired for reloading the compressor.

In the operation of the apparatus, let it be assumed first, that theparts are all in the position as indicated in Figure 2 in which case thecompressor is loaded. Upon an increase of pressure in the receiver Fbeyond a certain degree the pilot valve 34 will be lifted and in thefirst step will open the passage 40 shown in full lines to the vent 38and will supply fluid pressure from the pipe 37 through the passage 41shown in full lines so that the valve 36 will be moved to the left andthe passage 43 will be placed in communication with the vent 67. Thepipe 44 leading to the valve casing 45 will thus be vented to atmosphereand the pressure fluid from the pipe in the right hand end of the casing45 will shift the ball valves 46 and 47 so that the pipe 48 leading totwo of the clearance valves 23 at opposite ends of the compressorcylinders will be vented to atmosphere. The clearance valves will openand the compressor will be partially unloaded. l/Vhen the pilot valve 34of the regulator moves upwardly another step, a similar action willoccur in connection with the valves in the casing 53 and the pipes 54and 52 will be vented to atmosphere so that the other clearance valves23 will open and further unload the compressor. It is to be understoodthat there may be as many steps of clearance unloading provided asdesired, only two being shown for purposes of illustration.

To bring the second system of unloading into operation, the switch R isclosed which energizes the electro-magnet Q, raises the core W, rocksthe lever 58. closes the ball valve 62, opens the ball valve 63 andpermits pressure fluid to pass from pipe 37 around ball valve 63 to pipe65 and actuate the valve lifters J which hold the" inlet valves offtheir seats and produces unldading of the cylinders.

The compressor cylinders may be partially reloaded by reopening theswitch R which will restore the parts in the valve casing T to theposition shown in the drawings, but the compressor cannot be completelyreloaded unless the regulator arm 26 returns to reloading position byreduction of pressure in the receiver F. 011 starting for instance, theswitch. B may be closed which will energize the magnets Q, raise thecore W, rock the levers X and permit the ball valves in the casings Pand P to change position so that the pipe 50 and 56 are vented throughthe vents 5 around the ball valves 6. Pressure fluid in the pipes 44 and52 will force the valves in the casings 45 and 53 to the right as thedrawing is viewed so that the pipes 48 and 54 will be vented and theclearance valves will open and unload the compressor. The switch B maybe automatically operated as usual from the starting switch on themotor, but these connections are not shown as they are of usual andstandard construction.

I claim:

1. In a compressor, having unloading devices, a plurality of systems forcontrolling said devices, means for bringing one control system or theother into operation to unload the compressor, and means requiring theoperation of both systems to reload the compressor.

2. In a compressor having an unloading means, the combination of twosystems controlling the unloading means and interconnections between thesystenis so arranged that either sytsem may operate to unload thecompressor without the other, and maintain an unloaded condition untilboth systems operate to reload.

3. In a compressor, the combination of unloading devices for thecompressor, two control systems for actuating said devices, and

a controlling valve common to both systems so designed that if eithersystem tends to unload the compressor unloading will take place, but thecompressor will be maintained in unloaded condition unless both systemstend to reload.

4. In a compressor, the combination of one set of unloading devices forthe compressor. two control systems for actuating said de vices, and acontrolling valve for automatically bringing one system or the otherinto operation for unloading the compressor, and maintaining thecompressor in unloaded condition unless both systems tend to reload.

5. In a compressor, the combination of .one set of unloading devices forthe compressor, two control systems for actuating said devices, acontrolling Valve for automatically bringing one system or the otherinto operation for unloading the compressor and maintaining thecompressor in unloaded condition unless both systems tend to reload, andmeans for selecting one system or the other forunloading.

6. In a compressor, the combination of one set of unloading devices forthe compressor, two pilot systems for actuating said. devices, acontrolling valve for automatically bringingone system or the otherinto" operation for unloading the compressor and maintaining thecompressor in unloaded condition unless both systems tend to reload, andmeans for selecting one system for unloading while rendering the otherinoperative for unloading.

7. In a compressor, the combination of one set of unloading devices forthe compressor, two pilot systems for actuating said devices, acontrolling valve for automatically bringing one system or the otherinto operation for unloading the compressor and maintaining the unloadedcondition unless both systems tend to reload, means for selecting onesystem for unloading while rendering the other inoperative forunloading, and means for restoring the other system to loading operationso that both systems will tend to reload.

8. In a compressor, the combination of one set of unloading devices forthe compressor, two pilot systems for actuating said devices, one systemoperating to automatically unload and reload the compressor, the othersystem being manually controlled, and a controlling valve forautomatically bringing one system or the other into operation accordingto the system selected, and means for selecting one system or the othertrol means are placed in reloading position.

13. In a compressor having a plurality of unloading means, a pluralityof independent control means for selectively actuating said unloadingmeans, and further means to maintain the compressor in unloadedcondition until all of the control means are in position to reload.

14. In a compressor having a plurality of unloading means, a pluralityof independent control means for selectively actuating said unloadingmeans, and further means cooperating with said control means to maintainthe compressor in unloaded condition until all of said control means arein position for reloading.

15. In a compressor having a cylinder equipped with clearance control, aplurality of means for unloading said compressor, a plurality ofindependently operable control devices for selectively actuating saidunloading means, and further means to maintain the compressor inunloaded condition until all of the control devices are 'in position forreloading.

16. In a compressor having valves, means to hold a valve open, pressureresponsive means to actuate said valve holding means, electro-magneticmeans independent of said pressure responsive means to actuate saidvalve holding means, both said actuating means being coactive to theextent that the cooperation of both is required to permit closing of thevalve.

In testimony whereof I have signed this specification.

HARRY V. HAIGHT.

for operation as an unloader, said control- I ling valve maintaining thecompressor in unloaded condition unless both systems are operative forreloading.

9. In a compressor, means to reduce the load and a plurality of controlmeans independent of each other for actuating the load reducing meansbut interdependent for releasing said load reducing means.

10. In a compressor, means to unload the same, and a plurality ofindependent control means to actuate said unloading means, andadditional means' to maintain the unloaded condition until all thecontrol means cooperate to reload.

11. In a compressor, means to unload the same, a plurality ofindependent control means for actuating the unloading means, andadditional means to limit the reloading activity of one control meansuntil the cooperation of all control means is effected.

12. In a compressor, means to unload the same, a plurality ofindependent control means for actuating the unloading means,

